This application requests funding for an LSR II flow cytometer for quantitative analysis of fluorescence in fixed and living cells examined in numerous flow cytometric assays. The instrument will be installed in the newly built Interdisciplinary Research Complex (IRC) with laboratory space designed specifically for flow cytometry and will become part of the University of Wisconsin Paul P. Carbone Comprehensive Cancer Center's flow cytometry facility, which serves investigators from multiple departments throughout the University of Wisconsin research community. The mission of the IRC is to allow new scientific discoveries to move rapidly from research laboratories to clinical care settings. It will serve physicians and scientists that study many health- related cellular mechanisms, including organ rejection, cellular interactions in asthma, mechanisms of cancer development, and drug discovery. This benchtop cytometer will be equipped with a high-throughput screening device and 405, 488, 532, and 640 nm lasers. In addition to providing new features, the cytometer will relieve the demand for the existing LSRII. This instrument will come equipped with three components not currently available on the UW campus: a 532 nm laser, a 407 nm paired with 6 photomultiplier tubes, and a high-throughput sample-delivery device that will provide users with rapid, automated sample acquisition for experiments set-up in 96- or 348-well plates. In summary, the new cytometer will serve the needs of a broad NIH-funded scientific community at the University of Wisconsin campus and will expand the current technology available for fluorescence analysis. Public Health Relevance: The multi-color flow cytometer requested will be able to measure up to 18 different molecules simultaneously in or on the cells being studied;it will support the work of many different physicians and scientists who want to begin to understand how different molecular and cellular mechanisms work together in many different types of diseases. For example, it will enable transplant surgeons to dissect cellular mechanisms of organ rejection, allergists to understand immunological mechanisms in asthma, and basic scientists to understand multiple mechanisms of cancer development and examine the effect of many different compounds in the treatment of these diseases. Placement of this instrument in the Interdisciplinary Research Complex with close proximity to the hospital will allow new scientific discoveries to move rapidly from research laboratories to clinical care settings.